This is a hydraption pack,which can use for outdoor sports,like running,cycling,hiking,camping,climbing and daily training. 1.The fabric is nylon ripstop with PU coating and light waterproof function. 2.Size is L20*W8*H46cm 3.screen printing and reflective band on the front part for visibility and safety 4.front pocket with #5 zipper for keys, phone, snacks etc 5.external expandable stash zone with 2pcs durable buckles for towel,clothes etc 6.main pockets with #5 double-way zipper,you can put 1.0~2.0L bladder by velcro adjusted straps into inner lining pocket. 7.mesh shoulder padding and back for breathable,each ladder buckles can adjust the shoulder length 8.two sides can be used suitable for both left and right handers 9.special zipper puller 10.elastic band on the shoulder strap to hold the pipe. 11.chest straps with buckles can be adjusted to make confortable 12.wrist straps with buckles can stop shaking 13.inside silk binding to be strong 14.handle straps for easy carry this is a multifunctional style for outdoor sports